National Center for Biotechnology InformationHere's what the herpes virus looks like under the microscope.About one in six Americans between the ages of 14 and 49 is infected with herpes simplex virus type 2 (HSV-2), according to a survey presented at the 2010 National STD Prevention Conference this week.

Women and blacks are most likely to be infected, the study says. HSV-2 prevalence was nearly twice as high among women (20.9 percent) than men (11.5 percent), and was more than three times higher among blacks (39.2 percent) than whites (12.3 percent). The most affected group was black women, with a prevalence rate of 48 percent.

Herpes is a lifelong and incurable infection that can cause recurrent and painful genital sores. Medications can treat symptoms and prevent outbreaks, but the virus can be spread at any time. Research shows that people with herpes are two to three times more likely to acquire the AIDS virus, HIV. And, officials at the Centers for Disease Control and Prevention say that more than 80 percent of people with HSV are unaware of their infection.